Re: Engraver not getting an event

[David Kastrup]

Aaron Hill <address@hidden> writes:

> NOTE: I know that \bendAfter currently does not support all of the
> usages below; this all is coming from my investigation into how to
> enable such support.  My plan is to create a patched version of the
> engraver in Scheme as a proof-of-concept; and if it works, I can port
> the results back to C++ and submit a patch to the project.  But I have
> hit an unexpected stumbling block...
>
> Please consider the following:
>
> %%%%
> \version "2.19.82"
>
> debug_bend_engraver = #(make-engraver
>   (listeners
>     ((bend-after-event engraver event)
>       (format (current-error-port)
>         "\ndebug_bend_engraver: bend-after-event during ~a at ~a"
>         (ly:context-current-moment (ly:translator-context engraver))
>         (ly:prob-property (ly:event-property event 'music-cause)
> 'origin)))))
>
> \layout {
>   \context {
>     \Voice
>     \consists \debug_bend_engraver
>   }
> }
>
> \fixed g' {
>   g \bendAfter #-4 d2.
>   <g b>4 \bendAfter #-4 d2.
>   <g \bendAfter #-4 b>4 d2.
>   << { g4 \bendAfter #-4 } { b4 } >> d2.
> }
> %%%%
>
> I would expect the above to print out a debug line per each
> bend-after-event.  But oddly the third--the one attached to a note
> within a chord--seems to go missing.
>
> Adding in a \displayMusic doesn't really show anything different about
> the third usage of \bendAfter.  Just like the first and fourth
> occurrences, the bend-after-event is part of the articulations for the
> corresponding note-events.  (The second instance is unique in that the
> event is simply stored at the end of the chord's elements.)
>
> It is my understanding that the event-chord-iterator handles
> broadcasting all of the chord's elements, and then the
> rhythmic-music-iterator will take care of broadcasting the
> articulations for the note-events.  But that does not seem to be
> happening.
>
> Where have I gone wrong in my thinking?

_Either_ the Event_chord_iterator _or_ the Rhythmic_music_iterator are
doing the broadcasting of note events, depending on whether the notes
are within a chord or not.  _Only_ the Rhythmic_music_iterator
broadcasts articulations, so they are _only_ removed and broadcast for
non-chord notes, and actually only if there is a listener for them,
otherwise they are kept on the rhythmic event like articulations on
chord notes _always_ are.

If you want to do anything with chord note articulations, you have to
listen for the chord notes and look at their articulations property.

-- 
David Kastrup